Corrugated tubular member and method for producing the same

Abstract

To provide a technique for producing a corrugated tubular member that can inhibit increase of pressure loss at low cost.SOLUTION: A corrugated tubular member 1 comprises a tubular member having a tubular shape and being elastically bendable and deformable. On an outer circumferential surface 2, a corrugated surface shape is formed in which a recessed surface portion 21, 31 extending in a circumferential direction so as to be recessed inward in a radial direction and a protruding surface portion 22, 32 extending in the circumferential direction so as to protrude outward in the radial direction alternate along an axial direction. At least a part of the corrugated tubular member in the radial direction is formed as a foamed layer 4. An entirety of the corrugated tubular member including the outer circumferential surface 2 and an inner circumferential surface 3 in a thickness direction is integrally molded. In addition, the following element (a) or (b) is satisfied: (a) the corrugated surface shape is formed also on the inner circumferential surface 3 in addition to the outer circumferential surface 2, and a difference 3L between a recess and a protrusion in the radial direction in the corrugated surface shape on the inner circumferential surface 3 is less than a difference 2L between a recess and a protrusion in the radial direction in the corrugated surface shape on the outer circumferential surface 2, or (b) the inner circumferential surface 3 does not have the corrugated surface shape.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a corrugated tubular member, which is a type of tubular member, and a method for manufacturing the corrugated tubular member. [Background technology]

[0002] BACKGROUND ART Cylindrical members have been known for a variety of uses (see, for example, Patent Document 1). For example, a tubular member mounted on a vehicle is a refrigerant tube for connecting a heat exchanger to an infusion pump or a tank. The interior of the tubular member functions as a refrigerant flow path through which the refrigerant for the vehicle flows.

[0003] This type of cylindrical member must have a shape and length that correspond to the positional relationship of the device to be connected, for example, the positional relationship between the heat exchanger and the infusion pump described above. However, since the positional relationship of the devices to be connected varies depending on the type and combination of the devices, the environment in which the devices are placed, etc., it is not preferable from a cost perspective to individually set the shape and length of the tubular member depending on these factors. If the tubular member has a bendable structure, the shape and length of the tubular member can be changed in various ways, which is thought to increase the versatility of the tubular member.

[0004] A known bendable cylindrical member has a corrugated outer surface formed by alternating concave portions extending circumferentially and recessed radially inward and convex portions extending circumferentially and protruding radially outward along the axial direction. This type of cylindrical member can be deformed into various shapes and lengths by moving the adjacent convex (or concave) portions closer to or farther from each other. In this specification, this type of cylindrical member is referred to as a corrugated cylindrical member. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2022-51513 Summary of the Invention [Problem to be solved by the invention]

[0006] A typical corrugated tubular member has the above-described corrugated surface shape on both its outer and inner circumferential surfaces, but in such a corrugated tubular member, the fluid flowing inside the tube is exposed to the corrugated surface shape on the inner circumferential surface, which tends to increase pressure loss.

[0007] The above-mentioned Patent Document 1 introduces a cylindrical member for hot and cold water supply that has a double cylindrical structure in which a straight inner pipe is covered with a covering pipe that is a corrugated cylindrical member. If the inner peripheral surface of the corrugated cylindrical member is formed into a straight pipe, as in this cylindrical member, the cylindrical member can be made to have a structure that can be bent and deformed, and there is a possibility that an increase in pressure loss can be suppressed.

[0008] However, in order to manufacture a corrugated tubular member with a double-cylinder structure as introduced in Patent Document 1, it is necessary to use a special molding machine that can mold a straight inner tube and at the same time mold a cladding tube having a corrugated surface shape on the outer circumferential surface of the inner tube. Therefore, the corrugated tubular member with a double-cylinder structure has a problem of high manufacturing costs.

[0009] The present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide a technology for inexpensively manufacturing a corrugated tubular member that can suppress an increase in pressure loss. [Means for solving the problem]

[0010] The corrugated tubular member of the present invention that solves the above problems comprises: A cylindrical member that is cylindrical and can be elastically bent and deformed, The outer peripheral surface has a corrugated surface shape in which concave surface portions extending in the circumferential direction and recessed radially inward and convex surface portions extending in the circumferential direction and protruding radially outward are alternately arranged along the axial direction, At least a portion in the radial direction is made up of a foam layer, The entire thickness direction including the outer peripheral surface and the inner peripheral surface is integrally molded, The corrugated cylindrical member satisfies the following requirement (a) or (b): (a) the corrugated surface shape is provided on the inner peripheral surface in addition to the outer peripheral surface, a radial unevenness difference of the corrugated surface shape on the inner peripheral surface is smaller than a radial unevenness difference of the corrugated surface shape on the outer peripheral surface; (b) The inner peripheral surface does not have the corrugated surface shape.

[0011] Further, the method for manufacturing a corrugated tubular member of the present invention that solves the above problems includes: A method for manufacturing the corrugated tubular member of the present invention, This is a method for manufacturing a corrugated tubular member, which includes a molding process in which a foamed tubular material having a straight cylindrical shape is molded from the outer peripheral surface side using a mold block of a corrugator, and the corrugated surface shape is imparted to the outer peripheral surface of the foamed tubular material. [Effects of the Invention]

[0012] According to the corrugated tubular member and the manufacturing method thereof of the present invention, it is possible to inexpensively manufacture a corrugated tubular member that can suppress an increase in pressure loss. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 2 is an explanatory diagram for schematically explaining the corrugated tubular member of the first embodiment. [Figure 2] 1 is an explanatory diagram schematically illustrating a cross section of a corrugated tubular member according to a first embodiment. [Figure 3] 3A to 3C are explanatory views for schematically explaining a method for manufacturing the corrugated tubular member of Example 1. [Figure 4] FIG. 10 is an explanatory diagram schematically illustrating a cross section of a corrugated tubular member according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0014] The corrugated tubular member and the method for manufacturing the same of the present invention will be described below with specific examples.

[0015] The corrugated tubular member of the present invention is a tubular member that has a cylindrical shape and is elastically bendable. In other words, the corrugated tubular member of the present invention has flexibility that allows it to be compressed and deformed by an external force applied in the radial direction and be freely bent. The interior of the corrugated tubular member of the present invention functions as a flow path for fluid.

[0016] The corrugated tubular member of the present invention has a corrugated surface shape on its outer circumferential surface, in which concave surface portions extending in the circumferential direction and recessed radially inward and convex surface portions extending in the circumferential direction and protruding radially outward are alternately arranged along the axial direction, and at least a portion of the radial direction is formed by a foam layer, thereby allowing the corrugated tubular member of the present invention to be elastically bent and deformed.

[0017] The corrugated tubular member of the present invention satisfies the following requirement (a) or (b). (a) the corrugated surface shape is provided on the inner peripheral surface in addition to the outer peripheral surface, a radial unevenness difference of the corrugated surface shape on the inner peripheral surface is smaller than a radial unevenness difference of the corrugated surface shape on the outer peripheral surface; (b) The inner peripheral surface does not have the corrugated surface shape.

[0018] When the corrugated tubular member of the present invention satisfies the above-mentioned element (a), the radial unevenness of the corrugated surface shape on the inner peripheral surface is smaller than the radial unevenness of the corrugated surface shape on the outer peripheral surface. Therefore, although the corrugated tubular member has a corrugated surface shape, it is possible to suppress an increase in pressure loss of the fluid inside the tube.

[0019] When the corrugated tubular member of the present invention satisfies the above-mentioned element (b), the inner peripheral surface does not have a corrugated surface shape, and therefore, in the corrugated tubular member, the pressure loss caused by the corrugated surface shape itself is eliminated.

[0020] Furthermore, in the corrugated tubular member of the present invention, the entire thickness direction, including the outer peripheral surface and the inner peripheral surface, is integrally molded. Therefore, unlike the double-tube corrugated tubular member introduced in the above-mentioned Patent Document 1, which molds a straight inner tube and then molds a cladding tube having a corrugated surface shape on the outer peripheral side of the inner tube, there is no need to use a special molding machine.

[0021] Therefore, according to the corrugated tubular member of the present invention, it is possible to inexpensively manufacture a corrugated tubular member that can suppress an increase in pressure loss.

[0022] Hereinafter, the corrugated tubular member of the present invention and the method for manufacturing the corrugated tubular member of the present invention will be described for each of its components.

[0023] Hereinafter, unless otherwise specified, the manufacturing method of the present invention means the manufacturing method of the corrugated tubular member of the present invention. Furthermore, unless otherwise specified, the circumferential direction, radial direction, and axial direction respectively refer to the circumferential direction, radial direction, and axial direction of the corrugated tubular member of the present invention.

[0024] Unless otherwise specified, the numerical ranges "x to y" described in this specification include the lower limit x and the upper limit y. These upper and lower limit values, as well as the numerical values ​​listed in the embodiments, can be arbitrarily combined to form a numerical range. Furthermore, the upper and lower limit values ​​can be arbitrarily selected from within the numerical range.

[0025] The corrugated cylindrical member of the present invention is not limited to the above-mentioned tube for vehicle refrigerant, as long as it allows fluid to flow inside the cylindrical member. The fluid flowing through the flow path may be a liquid or a gas.

[0026] In the corrugated tubular member of the present invention, at least a portion of the radial direction is constituted by a foam layer. The foam layer may constitute the outer peripheral surface of the corrugated tubular member, the inner peripheral surface, or may be located between the outer peripheral surface and the inner peripheral surface. For convenience of flow inside the corrugated tubular member, the foam layer is preferably located closer to the outer peripheral surface than the inner peripheral surface in the radial direction of the corrugated tubular member, and it is more preferable that the corrugated tubular member have a non-foamed solid layer radially inward of the foam layer.

[0027] When the corrugated tubular member of the present invention has a foam layer and a solid layer, it is preferable that the inner peripheral surface of the corrugated tubular member is formed by the solid layer.

[0028] The corrugated tubular member of the present invention is elastically bendable. Therefore, it is necessary to select an elastically deformable material for the foam layer. If the corrugated tubular member of the present invention has the above-mentioned solid layer in addition to the foam layer, it is necessary to select an elastically deformable material for the solid layer as well.

[0029] The material for the foam layer is not particularly limited as long as it is elastically bendable and deformable, but it is preferable that the material has pores dispersed in a matrix of resin, rubber, elastomer, etc. The porosity and pore size of the foam layer are also not particularly limited. Furthermore, each pore in the foam layer may be independent, or at least some of the pores may be interconnected. In other words, the foam layer may be of either a closed-cell type or an open-cell type.

[0030] The pores of the foam layer may contain a gas, liquid, or solid that is different from the material that constitutes the matrix of the foam layer.

[0031] The matrix of the foam layer preferably contains a thermoplastic elastomer. Examples of thermoplastic elastomers that can be used for the foam layer include thermoplastic vulcanizates (TPV), thermoplastic olefinic elastomers (TPO), and thermoplastic styrenic elastomers (TPS). Of these, TPV is particularly preferred.

[0032] The solid layer is preferably made of a resin, rubber, or elastomer.Specific examples of materials preferably used for the solid layer include the above-mentioned thermoplastic elastomers, as well as polypropylene (PP), polyphenylene sulfide (PPS), and polyamide (PA).

[0033] Although the solid layer is intended to be a non-foamed layer, it is also acceptable for the solid layer to be a slightly foamed layer. This is because, when manufacturing the foamed cylindrical material that is the material for the corrugated tubular member of the present invention or when molding the corrugated tubular member of the present invention, the foaming agent, foam beads, etc. that are the material for the foamed layer may be mixed into the material for the solid layer, which may cause some foaming in the solid layer.

[0034] The expansion ratio of the solid layer can be 1 / 3 or less, 1 / 5 or less, or 1 / 8 of the expansion ratio of the foam layer.

[0035] The foam layer may be a single layer or multiple layers. For example, a protective layer may be provided radially outside the foam layer. The protective layer may be a foam layer having pores, or a non-foamed solid layer without pores.

[0036] The protective layer may be a single layer or a multi-layer consisting of two or more layers. The protective layer is preferably at least one of a layer having higher strength than the foam layer, a layer having better weather resistance than the foam layer, and a layer having better heat resistance than the foam layer.

[0037] The protective layer may be any layer capable of reinforcing the foam layer, and there are no particular limitations on the material or structure thereof, but it is preferable that the porosity of the protective layer be lower than that of the foam layer. Specifically, it is preferable that the porosity of the protective layer be less than 20%.

[0038] The protective layer may cover the entire surface of the foam layer from the outside, or may cover only a portion of the surface of the foam layer from the outside, but in order to reliably protect the foam layer with the protective layer, it is more preferable that the protective layer cover a large portion of the surface of the foam layer.

[0039] Specifically, when the surface area of ​​the foam layer is taken as 100%, the protective layer preferably covers 60% or more of it, more preferably 70% or more, and particularly preferably 80% or more. Note that the surface area of ​​the foam layer here refers to the apparent surface area calculated under the assumption that the foam layer has no pores.

[0040] When the protective layer is a foam layer, the material that constitutes the matrix of the protective layer may be the same as or different from that of the foam layer. When the protective layer is a non-foamed layer, the material of the protective layer may be the same as or different from that of the solid layer.

[0041] Furthermore, a layer with low porosity called a skin layer may be formed on the surface of the foam layer. This skin layer is formed when the foam layer is formed, and is formed by rapid cooling of the portion of the molding material that is in contact with the mold surface.

[0042] The skin layer is made of the same material as the foam layer and is formed integrally with the foam layer. The skin layer is a layer with a lower porosity than the other parts of the foam layer as described above, but can be distinguished from the solid layer in that it is very thin.

[0043] Specifically, the thickness of the skin layer can be said to be 1 mm or less. When the corrugated tubular member of the present invention has a solid layer, the thickness of the solid layer is preferably 1 / 10 or more, 1 / 5 or more, or 2 / 5 or more of the thickness of the foam layer. This can also be expressed as the radial length of the foam layer.

[0044] The foam layer and the solid layer may be made of various materials either singly or in combination.

[0045] Furthermore, it is also preferable to use, as the material for the foamed layer or solid layer, one or more selected from various resins, rubbers, or elastomers as the base material to which a filler such as metal or glass is added, in which case it is possible to impart various functionalities derived from the filler to the foamed layer or solid layer.

[0046] The corrugated tubular member of the present invention has a corrugated surface shape on its outer circumferential surface, in which concave and convex surface portions are alternately provided along the axial direction. The concave surface portions extend in the circumferential direction and are recessed radially inward, while the convex surface portions extend in the circumferential direction and are protruded radially outward. The corrugated surface shape may be said to have a plurality of concave portions and at least one convex portion, or to have a plurality of convex portions and at least one concave portion.

[0047] The corrugated tubular member of the present invention may have a corrugated surface shape on the entire outer peripheral surface or on only a part of the outer peripheral surface in the axial direction. For example, both axial end portions of the corrugated tubular member of the present invention may be straight tubular and have no corrugated surface shape on the outer peripheral surface.

[0048] The recessed depth of the concave portion may be uniform or non-uniform in the circumferential direction, and similarly, the protruding height of the convex portion may be uniform or non-uniform in the circumferential direction. Hereinafter, as necessary, the radially innermost portion of the concave surface portion will be referred to as the bottom portion of the concave surface portion, and the radially outermost portion of the convex surface portion will be referred to as the top portion of the convex surface portion.

[0049] Since the concave portion extends in the circumferential direction, the bottom of the concave portion also extends in the circumferential direction. Similarly, since the convex portion extends in the circumferential direction, the top of the convex portion also extends in the circumferential direction.

[0050] The corrugated tubular member of the present invention is a so-called corrugated pipe, and a suitable method for manufacturing the corrugated tubular member of the present invention is the manufacturing method of the present invention described below.

[0051] In the molding step of the manufacturing method of the present invention, the outer peripheral surface of the corrugated tubular member is molded. When manufacturing a corrugated tubular member by such a manufacturing method, in consideration of moldability, it is preferable that the convex and concave portions are continuous over the entire circumferential direction, and that adjacent convex and concave portions are separated from each other in the axial direction.

[0052] Therefore, in the corrugated tubular member of the present invention, adjacent concave portions may be continuous in a spiral shape, but in consideration of formability, it is preferable that adjacent concave portions are separated from each other. Similarly, in the corrugated tubular member of the present invention, adjacent convex portions may be continuous in a spiral shape, but in consideration of formability, it is preferable that adjacent convex portions are separated from each other.

[0053] When the corrugated surface shape has three or more concave portions, the distance between the bottoms of adjacent concave portions may be constant or may vary in the axial direction. In this case, the distance between the bottoms of adjacent concave portions may be constant or may vary over the entire circumference of the corrugated tubular member.

[0054] Similarly, when the corrugated surface shape has three or more convex portions, the distance between the apexes of adjacent convex portions may be constant or may vary in the axial direction. In this case, the distance between the apexes of adjacent convex portions may be constant or may vary around the entire circumference of the corrugated tubular member.

[0055] The corrugated tubular member of the present invention may have a corrugated surface shape only on the outer peripheral surface and not on the inner peripheral surface, or may have a corrugated surface shape on both the outer peripheral surface and the inner peripheral surface.

[0056] When the corrugated tubular member of the present invention has corrugated surface shapes on both the outer and inner peripheral surfaces, as in the above-mentioned element (a), the radial unevenness of the corrugated surface shape on the inner peripheral surface is smaller than the radial unevenness of the corrugated surface shape on the outer peripheral surface. The unevenness difference can also be referred to as the radial distance between the bottom of adjacent concave surface portions and the top of adjacent convex surface portions. Hereinafter, as necessary, the radial unevenness difference in the corrugated surface shape on the inner peripheral surface may be referred to as the inner surface unevenness difference, and the radial unevenness difference in the corrugated surface shape on the outer peripheral surface may be referred to as the outer surface unevenness difference.

[0057] In the corrugated cylindrical member of the present invention, it is sufficient that the difference in concavity and convexity of the inner surface is smaller than the difference in concavity and convexity of the outer surface, and there are no particular limitations on the dimensions of the difference in concavity and convexity of the outer surface and the difference in concavity and convexity of the inner surface, the ratio of the difference in concavity and convexity of the outer surface to the difference in concavity and convexity of the inner surface, etc. However, in order to reduce the pressure loss of the fluid inside the cylinder, it is preferable that the difference in concavity and convexity of the inner surface is small, and the smaller the difference in concavity and convexity of the inner surface is relative to the difference in concavity and convexity of the outer surface, the better.

[0058] Specifically, examples of suitable ranges for the difference in inner surface irregularities include 0.75 mm or less, 0.5 mm or less, and 0.25 mm or less. Although the difference in unevenness between the outer surface and the recesses does not contribute to reducing pressure loss, a larger difference in unevenness between the outer surface is preferable in order to allow the cylindrical member to bend and deform freely. From this perspective, suitable ranges for the difference in unevenness between the outer surface and the recesses are, for example, 0.75 mm or more, 1.0 mm or more, and 1.25 mm or more.

[0059] Further, examples of suitable ranges for the inner surface unevenness difference include 3 / 5 or less of the outer surface unevenness difference, 1 / 2 or less of the outer surface unevenness difference, and 2 / 5 or less of the outer surface unevenness difference.

[0060] As described above, the corrugated tubular member of the present invention can be manufactured by the manufacturing method of the present invention. The manufacturing method of the present invention includes a molding step, This is a process in which a foamed cylindrical material having a straight cylindrical shape is molded from the outer peripheral surface side by a mold block of a corrugator, and the corrugated surface shape is imparted to the outer peripheral surface of the foamed cylindrical material.

[0061] The foamed tube material to be fed to the corrugator has a straight cylindrical shape and is made of the material for the corrugated tubular member of the present invention. Specifically, the foamed tube material may contain a material such as resin, rubber, or elastomer that forms the matrix of the corrugated tubular member, a foaming agent that foams during the molding process, and foam beads that increase in volume during the molding process.

[0062] The foamed cylinder material may be formed into a straight cylinder, and may be produced by a known method such as extrusion molding or injection molding.

[0063] The term "straight cylindrical" used herein refers to a cylindrical shape without a corrugated outer circumferential surface, and the cross-sectional shape and axial shape of the foamed cylindrical material are not particularly limited. For example, the cross-sectional shape of the foamed cylindrical material may be circular or rectangular. The axial direction of the foamed cylindrical material may extend linearly or may be curved or bent.

[0064] The foamed tube material may be supplied to the corrugator in a cured state or in an uncured state. For example, an extruder for the foamed tube material may be provided upstream of the corrugator, and the foamed tube material and the corrugated tubular member may be continuously produced.

[0065] The corrugator includes mold blocks for molding the outer surface of the foamed cylindrical material. The mold blocks have a mold surface for imparting a corrugated surface shape, and two or more mold blocks are combined to form a cavity that surrounds the entire outer surface of the foamed cylindrical material.

[0066] The corrugator has a pressure reducing device or a pressure applying device for pressing the foamed cylinder material in the cavity against the mold surface. The pressure reducing device is a device for pressing the foamed cylinder material in the cavity against the mold surface by reducing the pressure inside the cavity. The pressure applying device is a device for pressing the foamed cylinder material in the cavity against the mold surface by supplying a fluid such as gas into the inside of the foamed cylinder material placed in the cavity.

[0067] In the molding process, the foamed cylindrical material is foamed and pressed against the mold surface of the mold block while increasing its apparent volume, so that the outer surface of the corrugated cylindrical member obtained in the molding process is given a corrugated surface shape that conforms to the mold surface.

[0068] On the other hand, since the inner surface of the foamed cylindrical material is not molded during the molding process, the inner surface of the corrugated cylindrical member obtained during the molding process has a so-called ``unexpected shape'' that corresponds to the corrugated surface shape of the outer surface.

[0069] The corrugated tubular member obtained by the manufacturing method of the present invention has a smaller inner surface unevenness difference than an outer surface unevenness difference. In order to make the inner surface unevenness difference smaller than the outer surface unevenness difference, it is preferable to use a corrugator having a pressure reducing device rather than a pressure applying device.

[0070] In addition, in order to make the difference in inner surface unevenness smaller than the difference in outer surface unevenness, the foamed cylinder material may have a multi-layer structure of two or more layers, and the layer located radially inner may be a layer that is less likely to deform than the layer located radially outer.

[0071] If the layer located radially inward is less likely to deform than the layer located radially outward, a corrugated surface shape is less likely to form on the inner surface of the foamed cylindrical material, and as a result, the difference in unevenness between the inner surface and the outer surface of the corrugated cylindrical member becomes smaller than the difference in unevenness between the outer surface and the inner surface.

[0072] Specifically, it is preferable that the radially outer portion of the multilayer foamed cylindrical material be made of a foam material layer and the radially inner portion be made of a solid material layer. The foam material layer is a layer that foams during the molding process and can be said to be the material for the foam layer in the corrugated tubular member of the present invention. On the other hand, the solid material layer is a layer that does not foam during the molding process or has a lower foaming ratio than the foam layer and can be said to be the material for the solid layer in the corrugated tubular member of the present invention.

[0073] Furthermore, according to the findings of the present inventors, when the expansion ratio of the foamed layer is large, the unevenness of the inner peripheral surface tends to be reduced and the surface tends to be smooth. Therefore, a larger expansion ratio of the foam layer is preferable, and specifically, preferred ranges of the expansion ratio can be 1.3 times or more, 1.4 times or more, 1.5 times or more, and 1.6 times or more.

[0074] The corrugated tubular member and the method for manufacturing the same of the present invention will be described below with specific examples.

[0075] Example 1 The corrugated tubular member of the first embodiment is a refrigerant tube mounted on a vehicle, and is manufactured by the manufacturing method of the present invention.

[0076] Fig. 1 is an explanatory diagram that schematically illustrates the corrugated tubular member of Example 1. Fig. 2 is an explanatory diagram that schematically illustrates a cross section of the corrugated tubular member of Example 1. Fig. 3 is an explanatory diagram that schematically illustrates a method for manufacturing the corrugated tubular member of Example 1.

[0077] The corrugated cylindrical member 1 of the first embodiment is mounted on a vehicle (not shown) and constitutes a part of a flow path for a vehicle refrigerant. 1, the corrugated tubular member 1 of Example 1 has a substantially cylindrical shape. In the corrugated tubular member 1 of Example 1, a corrugated surface shape is formed on an outer peripheral surface 2 and an inner peripheral surface 3 thereof.

[0078] As shown in Figure 2, the corrugated tubular member 1 of Example 1 has a single-layer structure composed only of a foam layer 4. The foam layer 4 is made of foamed TPV. Specifically, the matrix of the foam layer 4 is made of TPV, a type of plastic elastomer. The foam layer 4 is made from a mixture of TPV pellets and a foaming agent, and air bubbles are formed in the foam layer 4 during the extrusion and molding processes described below.

[0079] An interior 10 of the corrugated cylindrical member 1 is defined by an inner circumferential surface 3 of the corrugated cylindrical member 1 and functions as a flow path for the vehicle refrigerant.

[0080] The corrugated surface shape of the outer peripheral surface 2 of the corrugated tubular member 1 is such that concave surface portions that extend circumferentially and sink radially inward and convex surface portions that extend circumferentially and protrude radially outward are alternately provided along the axial direction. The concave surface portions on the outer peripheral surface 2 are referred to as outer peripheral concave surface portions 21, and the convex surface portions on the outer peripheral surface 2 are referred to as outer peripheral convex surface portions 22.

[0081] The corrugated surface shape of the inner peripheral surface 3 of the corrugated tubular member 1 also has concave surface portions that extend circumferentially and sink radially inward, and convex surface portions that extend circumferentially and protrude radially outward, arranged alternately along the axial direction. The concave surface portions on the inner peripheral surface 3 are referred to as inner peripheral concave surface portions 31, and the convex surface portions on the inner peripheral surface 3 are referred to as inner peripheral convex surface portions 32.

[0082] The inner peripheral concave surface portion 31 is located radially inside the corresponding outer peripheral concave surface portion 21 , and the inner peripheral convex surface portion 32 is located radially inside the corresponding outer peripheral convex surface portion 22 .

[0083] In the corrugated tubular member 1 of Example 1, the distance between adjacent outer peripheral concave surface portions 21 is approximately constant in the circumferential direction and the axial direction, and the distance between adjacent outer peripheral convex surface portions 22 is approximately constant in the circumferential direction and the axial direction. In addition, the distance between adjacent inner peripheral concave surface portions 31 is approximately constant in the circumferential direction and the axial direction, and the distance between adjacent inner peripheral convex surface portions 32 is approximately constant in the circumferential direction and the axial direction.

[0084] In the corrugated cylindrical member 1 of Example 1, the outer surface unevenness difference 2L is 1 mm, and the inner surface unevenness difference 3L is 0.5 mm.

[0085] The manufacturing method of Example 1 will be described below. The manufacturing method of Example 1 includes an extrusion step and a molding step.

[0086] Among these, the extrusion process is a process for producing a straight cylindrical foamed cylindrical material 6. The molding process is a process for molding the foamed cylindrical material 6 from the outer peripheral surface 62 side by a mold block 8 of a corrugator 7, and imparting a corrugated surface shape to the outer peripheral surface 62 of the foamed cylindrical material 6.

[0087] In the extrusion step, TPV and foam beads were placed in a feeder of an extruder (not shown), and passed through a mold of the extruder to extrude a straight cylindrical foamed cylindrical material 6 having a foamed material layer 64 . The extrusion molding machine was disposed upstream of a corrugator 7, and the foamed cylinder material 6 produced in the extrusion process was supplied to the corrugator 7 in an uncured state.

[0088] 3, the corrugator 7 has a plurality of mold blocks 8. Each mold block 8 has a half-split shape, and two mold blocks 8 are combined to form a cavity. The foaming cylinder material 6 is placed inside the cavity.

[0089] The corrugator 7 is equipped with a decompression device (not shown). A through hole 80 that connects the inside and outside of the cavity is formed in the mold block 8, and the decompression device is connected to the through hole 80 to reduce the pressure inside the cavity. The mold block 8 is heated, and the foaming cylinder material 6 in the cavity is softened and deformable.

[0090] When the pressure inside the cavity is reduced by the pressure reducing device, the foamed cylinder material 6 inside the cavity is foamed and pressed against the mold surface 81 of the mold block 8. As a result, a corrugated surface shape is imparted to the outer circumferential surface 62 of the foamed cylinder material 6. The foamed cylinder material 6 is cooled and hardened to obtain the corrugated tubular member 1 of Example 1 having a corrugated surface shape on the outer circumferential surface 2.

[0091] In the molding process, the inner peripheral surface 3 of the foamed cylindrical material 6 is attracted toward the mold surface 81 along with the outer peripheral surface 2. As a result, a corrugated surface shape is also imparted to the inner peripheral surface 3 of the foamed cylindrical material 6. As a result, in the corrugated tubular member 1 of Example 1, a corrugated surface shape is also formed on the inner peripheral surface 3.

[0092] In the manufacturing method of Example 1, the expansion ratio of the corrugated tubular member 1 was 1.5 times. In other words, the volume of the corrugated tubular member 1 was 1.5 times the volume of the foamed tubular material 6.

[0093] The mold block 8 and the foamed cylindrical material 6 move relative to each other in the axial direction of the foamed cylindrical material 6. Therefore, the foamed cylindrical material 6 is successively molded along the axial direction by the mold block 8, and a long corrugated cylindrical member 1 is obtained.

[0094] The corrugated tubular member 1 of Example 1 has a corrugated surface shape on the outer peripheral surface 2 and the inner peripheral surface 3, and is made of foamed TPV, so that it can be elastically bent and deformed.

[0095] In the corrugated tubular member 1 of Example 1, the inner surface unevenness difference 3L is smaller than the outer surface unevenness difference 2L. Therefore, in the corrugated tubular member 1 of Example 1, an increase in fluid pressure loss in the tube interior 10 is suppressed, and the corrugated tubular member 1 has a corrugated surface shape on the outer peripheral surface 2 and can be easily bent and deformed.

[0096] Furthermore, the corrugated tubular member 1 of Example 1 has a single-layer structure consisting of only the foam layer 4, and is integrally molded in its entirety in the thickness direction, including the outer peripheral surface 2 and the inner peripheral surface 3. Therefore, unlike the corrugated tubular member of the double-tube structure described above, the corrugated tubular member 1 of Example 1 can be molded using a general corrugator 7.

[0097] As a result, according to the manufacturing method of Example 1, the corrugated tubular member 1 capable of suppressing an increase in pressure loss can be manufactured at low cost. Moreover, the corrugated tubular member 1 of Example 1 is capable of suppressing an increase in pressure loss and is manufactured at low cost.

[0098] Example 2 The corrugated tubular member 1 of Example 2 differs from the corrugated tubular member 1 of Example 1 in that it has a two-layer structure and in the shape of the inner peripheral surface 3. Otherwise, the corrugated tubular member 1 of Example 2 is substantially the same as the corrugated tubular member 1 of Example 1. Below, the corrugated tubular member 1 of Example 2 and its manufacturing method will be described, focusing on the differences from the corrugated tubular member 1 of Example 1.

[0099] FIG. 4 is an explanatory diagram showing a schematic cross section of the corrugated tubular member 1 of the second embodiment.

[0100] As shown in FIG. 4, the corrugated tubular member 1 of Example 2 has a two-layer structure in which a solid layer 5 is formed on the radially inner side of a foam layer 4 . The solid layer 5 is made of non-foamed PP.

[0101] In the corrugated tubular member 1 of Example 2, a corrugated surface shape is formed on the outer peripheral surface 2, but the inner peripheral surface 3 is flat and does not have a corrugated surface shape. The difference in unevenness 2L on the outer surface of the corrugated cylindrical member 1 of Example 2 is 1 mm.

[0102] In the manufacturing method of Example 2, in the extrusion process, a foamed cylindrical material having a two-layer structure with a foamed material layer on the radially outer side and a solid material layer on the radially inner side was extruded using a method known as two-color extrusion molding or co-extrusion molding.

[0103] More specifically, in the extrusion process, the material for the foamed material layer and the material for the solid material layer of the foamed cylindrical material were separately placed in the feeders of the extruder (not shown), and then extruded through the mold of the extruder to form a straight cylindrical foamed cylindrical material having the foamed material layer and the solid material layer.

[0104] The foamed cylinder material was then fed to a corrugator to form the corrugated tubular member 1 of Example 2 in substantially the same procedure as the forming process in the manufacturing method of Example 1.

[0105] In the manufacturing method of Example 2, the expansion ratio of the foamed layer 4 was 1.5 times, and the solid layer 5 was not expanded. The expansion ratio of the solid layer 5 can be said to be 1 time.

[0106] The corrugated tubular member 1 of Example 2 has a corrugated surface shape, which has an outer peripheral concave surface portion 21 and an outer peripheral convex surface portion 22, only on the outer peripheral surface 2, and does not have a corrugated surface shape on the inner peripheral surface 3. However, the corrugated tubular member 1 of Example 2 has a corrugated surface shape on the outer peripheral surface 2, the foamed layer 4 is made of foamed TPV, and the solid layer 5 is also made of deformable PP. Therefore, the corrugated tubular member 1 of Example 2 can also be elastically bent and deformed.

[0107] In the corrugated tubular member 1 of Example 2, there is almost no unevenness on the inner surface. Therefore, the corrugated tubular member 1 of Example 2 also has a corrugated surface shape on the outer circumferential surface 2 and can be easily bent and deformed while suppressing an increase in pressure loss of the fluid inside the tube 10.

[0108] Furthermore, the corrugated tubular member 1 of Example 2 has a two-layer structure consisting of a foam layer 4 and a solid layer 5, but the foam layer 4 and the solid layer 5 are integrally molded. Therefore, it can be said that the entire corrugated tubular member 1 in the thickness direction, including its outer peripheral surface 2 and inner peripheral surface 3, is integrally molded. Therefore, the corrugated tubular member 1 of Example 2 can also be molded using a general corrugator.

[0109] As a result, according to the manufacturing method of Example 2, the corrugated tubular member 1 capable of suppressing an increase in pressure loss can be manufactured at low cost. Moreover, the corrugated tubular member 1 of Example 2 is capable of suppressing an increase in pressure loss and is manufactured at low cost.

[0110] Although the present invention has been described above, the present invention is not limited to the above-described embodiments, etc., and it is possible to implement the present invention by appropriately extracting and combining elements described in the embodiments, etc., and to make various modifications within the scope that does not deviate from the spirit of the present invention. Furthermore, the specification of the present invention discloses not only the citation relationships of the claims at the time of filing but also the technical idea of ​​appropriately combining the matters described in the claims. [Explanation of symbols]

[0111] 1: Corrugated cylindrical member 21: Concave outer periphery (concave) 22: Convex outer periphery (convex) 2: Outer surface 3: Inner surface 31: Inner concave surface portion (concave surface portion) 32: Inner convex surface portion (convex surface portion) 2L: Difference in unevenness on the outer surface 3L: Difference in unevenness on the inner surface 4: Foam layer 5: Solid layer 6: Foaming tube material 62: Outer surface of foaming tube material 64: Foam material layer 7: Corrugator 8:Mold block

Claims

1. A cylindrical member that is cylindrical and can be elastically bent and deformed, The outer peripheral surface has a corrugated surface shape in which concave surface portions extending in the circumferential direction and recessed radially inward and convex surface portions extending in the circumferential direction and protruding radially outward are alternately arranged along the axial direction, At least a portion in the radial direction is made up of a foam layer, The entire thickness direction including the outer peripheral surface and the inner peripheral surface is integrally molded, A corrugated tubular member that satisfies the following requirement (a) or (b): (a) The corrugated surface shape is provided on the inner peripheral surface in addition to the outer peripheral surface, a radial unevenness difference of the corrugated surface shape on the inner peripheral surface is smaller than a radial unevenness difference of the corrugated surface shape on the outer peripheral surface; (b) The inner peripheral surface does not have the corrugated surface shape.

2. Satisfies the above (a), The difference in the radial unevenness of the corrugated surface shape on the outer peripheral surface is 1 mm or more, The corrugated tubular member according to claim 1 , wherein the difference in radial irregularities in the corrugated surface shape on the inner peripheral surface is 0.5 mm or less.

3. The corrugated tubular member according to claim 1 or 2, further comprising a solid layer disposed radially inside the foam layer.

4. The corrugated tubular member according to claim 1 or 2, wherein the foam layer contains a thermoplastic elastomer as a material.

5. A method for manufacturing the corrugated tubular member according to claim 1 or 2, comprising: A method for manufacturing a corrugated tubular member, comprising a molding process in which a foamed tubular material having a straight cylindrical shape is molded from the outer peripheral surface side using a mold block of a corrugator to impart the corrugated surface shape to the outer peripheral surface of the foamed tubular material.

6. At least a part of the foamed cylinder material in the radial direction is made of a foamed material layer that is foamed in the molding process and becomes the foamed layer, The method for manufacturing a corrugated tubular member according to claim 5, wherein the foam layer has an expansion ratio of 1.5 or more.

7. The method for manufacturing a corrugated tubular member according to claim 5, wherein the foamed cylindrical material has a multi-layer structure having a foamed material layer on the radially outer side and a solid material layer on the radially inner side.

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